Muffler

ABSTRACT

A muffler including a venturi inlet to degrade and dissipate the energy of the incoming gases and a plurality of transverse baffle plates having offset openings therethrough to cause a change in direction of the gas flow through the muffler to absorb gas flow energy with minimal increase in back pressure. Perforated tubes can be employed in the offset openings in the baffle plates.

United States Patent Kirkland, Jr. et al. [4 July 25, 1972 [541 MUFFLER 2,395,005 2/1946 Kuhn ..1s1/49 [72] Inventors: Kenneth C. Kirkland, Jr.; Raymon E. 3? i bah 3,515,242 6/1970 Lyttle ..1s1/s7 x [73] Assignee: Stemco Manufacturing Company, Inc.,

Longview, FOREIGN PATENTS OR APPLICATIONS 1,162,634 2/1964 Germany ..1s1/s7 [22] sept'uwm 512,982 2/1955 Italy ..1s1/47 [21] App1.No.: 71,297

[ 52] U.S. Cl ..18l/49, 181/57 [51] ..F0ln H08 [58] Field of Search ..181/49, 57, 53, 69, 35 R, 63, 181/59, 47 R, 54, 55

[56] References Cited I UNITED STATES PATENTS 2,940,538 6/1960 Billey 181/63 2,115,128 4/1938 Starkweather et a1.. ..l8l/57 2,618,353 11/1952 l-ledrick ....18l/63 UX 1,631,391 6/1927 Williams ..181/69 Primary ExaminerRichard B. Wilkinson Assistant Examiner-John F. Gonzales Attorney-Schovee and Boston [5 7] ABSTRACT A muffler including a venturi inlet to degrade and dissipate the energy of the incoming gases and a plurality of transverse baffle plates 2 having offset openings therethrough to cause a change in direction of the gas flow through the muffler to absorb gas flow energy with minimal increase in back pressure. Perforated tubes can be employed in the offset openings in the baffle plates.

7 Claims, 2 Drawing Figures Patented July 2 5,- 1972 mvsmoxs KENNETH c. KIRKLAND, JR.

BY RAYMON E. HUNT XM v ATTORNEYS MUFFLER BACKGROUND OF THE INVENTION This invention relates to mufi'lers and in particular to an improved muffler construction.

While it is known in the prior art to employ venturi devices for throttling the gas flow through a muffler and while it is also known to employ baffle plates having offset openings therethrough to provide an S" flow pattern to absorb flow energy, it is not known to combine the two devices. Further, the particular construction of the present invention is not only new but it employs a particular venturi configuration which, in itself, is detrimental causing an increase in the noise level, but which, in the particular combination with the offset flow pattern, provides a synergistic effect such that when combined with the particular offset flow pattern provides greater attenuation or sound reduction than does the offset flow pattern by itself.

SUMMARY OF THE INVENTION The present invention comprises a muffler having an enclosed, hollow, elongated housing defining a chamber, the housing having an inlet opening at one end and a discharge opening at the other end thereof. A relatively short inlet tube extends through the inlet opening and terminates in a discharge opening (a venturi) of reduced diameter. A plurality of solid baffle plates extend transversely across the chamber, the baffle plates having openings offset from the longitudinal axis of the housing, with the openings in adjacent baffles being offset from each other on opposite sides of said axis, to cause the gas flow through the muffler to change direction as it passes from the inlet opening to the discharge opening thereof. This combination of the offset flow pattern and the venturi inlet provides an unexpected improvement in noise reduction.

BRIEF DESCRIPTION OF THE DRAWING The present invention will be more fully understood by reference to the following detailed description thereof, when read in conjunction with the attached drawing, wherein like reference numerals refer to like elements, and wherein:

FIG. 1 is a vertical cross-sectional view through one muffler embodiment of the present invention; and

FIG. 2 is a vertical, cross-sectional view through another muffler embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference now to the drawing, FIG. I shows one embodiment of the present invention comprising a muffler including a hollow, elongated housing 12 having venturi inlet 14 and means 16 for causing an offset gas flow pattern through the muffler 10. The housing 12 encloses a chamber 18 and includes an inlet opening 20 thereinto and a discharge opening 22 therefrom.

The venturi inlet 14 is formed, in this embodiment, by a pair of battle plates 24 and 26 and an inlet tube 28. The baffle plates 24 and 26 extend transversely across the chamber 18 adjacent an inlet end 30 thereof. Each plate 24 and 26 has a centrally positioned opening 32 and 34 respectively,

therethrough, located on the longitudinal axis of the chamber 18. The inlet tube 28 has a cross-sectional shape the same as that of the openings 32 and 34, and extends through said openings 32 and 34 and is connected to the plates 24 and 26 at the openings therein. The inlet tube 28 includes a plutality of perforations 36 therethrough, providing communication between the inlet opening 20 and a chamber 38 between the plates 22 and 24. The inlet tube 28 terminates in acentrally positioned, relatively small discharge opening 40 in an end plate 42. The relatively small internal diameter of the opening 40 compared to the internal diameter of the inlet tube 28, provides the venturi effect which effectively throttles down the flow of gases at the start of their flow path through the muffler 10. This venturi effect degrades and dissipates the energy of the gases. The venturi inlet 14 can have many different configurations and constructions and need not be formed as shown in FIG. 1.

The means 16 for causing an offset flow pattern is formed, in this embodiment, by a pair of battle plates 44 and 46, each having an opening 48 and 50, respectively, therethrough. The openings 48 and 50 are each offset radially from the longitudinal axis of the housing I2, and the adjacent openings 48 and 50 are also offset on opposite sides of the longitudinal axis from each other. Flow tubes 52 and 54 extend through the openings 48 and 50, respectively, and are connected to the plates 44 and 46, respectively, at the openings therein. Both of the tubes 52 and 54 can be perforated. The above described construction causes the main flow of gases through the muffler 10 from the inlet opening 20 to the discharge opening 22 to gradually change direction causing the gases to flow in an 8" pattern. By changing the direction of the gases gradually, flow energy is absorbed with a minimal increase in back pressure.

The discharge opening 22 is formed by a pair of baffle plates 60 and 62, and a discharge tube 64. The plates 60 and 62 extend transversely across the chamber 18 adjacent a discharge end 66 thereof. Each plate 60 and 62 has a centrally positioned opening 68 and 70, respectively, therethrough, located on the longitudinal axis of the chamber 18. The discharge tube 64 has a cross-sectional shape the same as that of the openings 68 and 70, and extends through the openings 68 and 70 and is connected to the plates 60 and 62 at said openings. The discharge tube 64 includes a plurality of perforations 72 therethrough, providing communication between the discharge opening 22 and a chamber 74 between the plates 60 and 62.

In addition to the chambers 38 and 74, the chamber 18 is broken up into a chamber 76 between baffle plates 26 and 44, a chamber 78 between baffle plates 44 and 46, and a chamber 80 between baffle plates 46 and 60. In addition to the throttling of the incoming gases that takes place at the venturi inlet 14, additional throttling takes place in the chambers 76, 78 and 80 due to the relatively small cross-sectional area of the tubes 52,54, and 64, relative to the larger cross-sectional area of the chamber 18.

The exact volume of the various chambers, the lengths of the various tubes, and the ratio of perforated hole area to chamber volume, for a specific muffler designed for use with a specific exhaust system will depend on the frequencies and other factors to be encountered in the exhaust system, as will be evident to one skilled in the art. The cross-section of the chamber 18 is preferably either circular or elliptical (the term generally circular is hereby defined for use in the present specifications and claims as including circular and elliptical) and 'the cross-sections of the tubes 28, 52, 54, and 64 are preferably circular. Various known perforation patterns and constructions can be used in the tubes 28, 52, 54, AND 64. To provide the offset gas flow pattern a series" of one or more baffle plates is used, each plate having an opening therethrough offset from the longitudinal axis of the chamber 18, and the openings in adjacent baffle plates are offset from each other on opposite sides of the longitudinal axis of the chamber 18. While only two baffle plates having offset openings are shown, more can be used.

FIG. 2 shows another muffler embodiment of the invention, which is similar to that of FIG. 1 except for the use of a different venturi inlet and offset bafile construction. All parts of the muffler 90 that are identically the same in the muffler 10 have the same reference numerals. The muffler 90 employs a venturi inlet 92 fonned of the baffle plates 24 and 26 and an inlet tube 94 that includes a tapering portion 96 that tapers down to a reduced internal diameter at a smaller straight portion 98. The muffler 90 does not include any flow tubes connected to the baffle plates 44 and 46; the offset flow pattern is created simply by the openings 48 and 50, respectively in plates 44 and 46.

for causing the gas flow to change directions includes means for throttling down the flow of gases through said chamber.

short, axially extending flow tube connected to each baffle plate at the opening therein.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove, and as defined in the appended claims. 5

We claim:

I. A muffler comprising:

a. a hollow, enclosed, straight, elongated, housing defining a chamber of generally circular cross-section, said housing having a coaxially located inlet opening at one end into said chamber and a discharge opening out of said chamber at the other end;

b. venturi means positioned adjacent said inlet opening for throttling down gas flow into said chamber, said venturi means comprising a relatively short inlet tube extending through said inlet opening coaxially into said chamber, said tube terminating in a discharge opening of reduced internal diameter for throttling down the gases at the start of their flow path through the muffler; and

c. means in said chamber for causing the gas flow through said chamber to change directions as it flows from said inlet opening to said outlet opening, comprising a series of solid baffle plates extending transversely across said chamber, each of said baffle plates having an opening extending therethrough offset from the longitudinal axis of 25 said housing, and the openings in adjacent baffle plates being offset from each other on opposite sides of said axis.

2. The apparatus according to claim 1 wherein said means 3. The apparatus according to claim 1 including a relatively 4. The apparatus according to claim 1 wherein said inlet tube extends from said inlet opening to an axially located opening in a bafile plate positioned adjacent an inlet end of said housing, said baffle plate and said inlet end of said housing forming a first chamber, and said inlet tube including perforations therethrough into said first chamber.

5. The apparatus according to claim 1 wherein said inlet tube consists of a main tube body of relatively larger internal diameter and of generally circular cross-section, a discharge tube of relatively smaller internal diameter, and of generally circular cross-section, and a tapering, tubular portion connecting said main tube body and said discharge tube.

6. The apparatus according to claim 1 wherein said inlet tube comprises a main tube body of generally circular crosssection and a ring shaped plate connected to the discharge end of said inlet tube, said ring shaped plate having a central opening therein of generally circular cross-section and of smaller internal diameter than that of said main tube body.

7. The apparatus according to claim 1 including a first baffle plate adjacent said inlet opening of said muffler and having a coaxially positioned opening therein, said venturi means including an inlet tube positioned in said inlet opening and extending coaxially to said opening in said first baffle plate and being connected to said first baffle plate, said inlet tube including perforations extending therethrough and having a discharge opening of reduced internal diameter; a second baffle plate adjacent said discharge opening of said muffler and having a coaxially positioned opening therein, a discharge tube extending coaxially from said discharge opening to said opening in said second baffle plate and being connected to said second baffle plate, said discharge tube including perforations extending therethrough, and said offset openings in said series of baffle plates having a relatively short, axially extending, flow pipe connected at a forward end thereof to each of i said offset openings and extending toward the end of said housing having said discharge opening, and terminating short of the next adjacent baffle plate.

* a a a a 

1. A muffler comprising: a. a hollow, enclosed, straight, elongated, housing defining a chamber of generally circular cross-section, said housing having a coaxially located inlet opening at one end into said chamber and a discharge opening out of said chamber at the other end; b. venturi means positioned adjacent said inlet opening for throttling down gas flow into said chamber, said venturi means comprising a relatively short inlet tube extending through said inlet opening coaxially into said chamber, said tube terminating in a discharge opening of reduced internal diameter for throttling down the gases at the start of their flow path through the muffler; and c. means in said chamber for causing the gas flow through said chamber to change directions as it flows from said inlet opening to said outlet opening, comprising a series of solid baffle plates extending transversely across said chamber, each of said baffle plates having an opening extending therethrough offset from the longitudinal axis of said housing, and the openings in adjacent baffle plates being offset from each other on opposite sides of said axis.
 2. The apparatus according to claim 1 wherein said means for causing the gas flow to change directions includes means for throttling down the flow of gases through said chamber.
 3. The apparatus according to claim 1 including a relatively short, axially extending flow tube connected to each baffle plate at the opening therein.
 4. The apparatus according to claim 1 wherein said inlet tube extends from said inlet opening to an axially located opening in a baffle plate positioned adjacent an inlet end of said housing, said baffle plate and said inlet end of said housing forming a first chamber, and said inlet tube including perforations therethrough into said first chamber.
 5. The apparatus according to claim 1 wherein said inlet tube consists of a main tube body of relatively larger internal diameter and of generally circular cross-section, a discharge tube of relatively smaller internal diameter, and of generally circular cross-section, and a tapering, tubular portion connecting said main tube body and said discharge tube.
 6. The apparatus according to claim 1 wherein said inlet tube comprises a main tube body of generally circular cross-section and a ring shaped plate connected to the discharge end of said inlet tube, said ring shaped plate having a central opening therein of generally circular cross-section and of smaller internal diameter than that of said main tube body.
 7. The apparatus according to claim 1 including a first baffle plate adjacent said inlet opening of said muffler and having a coaxially positioned opening therein, said venturi means including an inlet tube positioned in said inlet opening and extending coaxially to said opening in said first baffle plate and being connected to said first baffle plate, said inlet tube including perforations extending therethrough and having a discharge opening of reduced internal diameter; a second baffle plate adjacent said discharge opening of said muffler and having a coaxially positioned opening therein, a discharge tube extending coaxially from said discharge opening to said opening in said second baffle plate and being connected to said second baffle plate, said discharge tube including perforations extending therethrough, and said offset openings in said series of baffle plates having a relatively short, axially extending, flow pipe connected at a forward end thereof to each of said offset openings and extending toward the end of said housing having said discharge opening, and terminating short of the next adjacent baffle plate. 